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QOS for 911 Voice Calls

Unanswered Question
Nov 18th, 2005
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I have a Cisco 4507 switch with IP Phones connected to it. On IP Phones Port, I have command enabled, "AUTO QOS VOIP CISCO-PHONE"

4507 port 5/18 connects to 2821 FE0/0 router via DOT1Q trunk to carry both voice and data traffic.

On 4507 5/18 port I enabled, "AUTO QOS VOIP TRUST"

I think swithch is now ready to priroitize Voice Traffic. What kind of QOS I need at the 2821 router. 2821 has (2) PRI T1 connects to PSTN, and (2) T1 MLPPP connects to the Internet. Client has a branch locations that they will connect via VPN. My first priority to make sure that 911 calls routed very quickly as it will since it will go through the PSTN, and I have "AUTO QOS VOIP TRUST' enabled on a Switch port, but when the calls come back or 911 calls back the router's FE0/0 is sharing the traffic between voice and data so what is recommended to priortize voice traffic back from the Router to the Switch.


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Chris Deren Sun, 11/20/2005 - 10:30
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To route 911 as quickly as possible, check the "urgent priority" on the CCM 911 route pattern, here is the definition:

"If the dial plan contains overlapping route patterns, Cisco CallManager would not route the call until the interdigit timer expires (even if it is possible to dial a sequence of digits to choose a current match). Check this check box to interrupt interdigit timing when Cisco CallManager must route a call immediately."

As to the QoS, you can not define higher priority just for 911 calls, you can classify voice traffic with higher priority and utiulize Low Latency Queing (LLQ) to accomplish that. Check out QoS SRND doc for configuration examples and more details at www.cisco.com/go/srnd.



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